System for preparing a patient&#39;s tibia in an orthopaedic joint replacement procedure

ABSTRACT

An orthopaedic joint replacement system is shown and described. The system includes a number of prosthetic components configured to be implanted into a patient&#39;s knee. The system also includes a number of surgical instruments configured for use in preparing the bones of the patient&#39;s knee to receive the implants. A method or technique for using the surgical instruments to prepare the bones is also disclosed.

The present application claims priority under 35 U.S.C. §119 to U.S.Patent Application Ser. No. 62/338,284, filed May 18, 2016, and havingthe title “SYSTEM AND METHOD FOR PREPARING A PATIENT'S TIBIA IN ANORTHOPAEDIC JOINT REPLACEMENT PROCEDURE,” which is herein incorporatedby reference in its entirety.

CROSS-REFERENCE TO RELATED APPLICATIONS

Cross reference is made to copending U.S. Patent Application Ser. No.62/338,276 entitled “SYSTEM AND METHOD FOR PREPARING A PATIENT'S FEMURIN AN ORTHOPAEDIC JOINT REPLACEMENT PROCEDURE;” and copending U.S.Patent Application Ser, No. 62/338,468 entitled “SYSTEM AND METHOD FORPREPARING A PATIENT'S BONE TO RECEIVE A PROSTHETIC COMPONENT,” each ofwhich is assigned to the same assignee as the present application, eachof which is filed concurrently herewith, and each of which is herebyincorporated by reference.

Cross reference is made to copending U.S. patent application Ser. No.______ entitled “ORTHOPAEDIC INSTRUMENT SYSTEM FOR SURGICALLY-PREPARINGA PATIENT'S TIBIA” (Attorney Docket No. 265280-264620, DEP6728USNP); andcopending U.S. patent application Ser. No. ______ entitled “METHOD FORPREPARING A PATIENT'S TIBIA IN AN ORTHOPAEDIC JOINT REPLACEMENTPROCEDURE” (Attorney Docket No. 265280-265863, DEP6728USNP2), each ofwhich is assigned to the same assignee as the present application, eachof which is filed concurrently herewith, and each of which is herebyincorporated by reference.

TECHNICAL FIELD

The present disclosure relates generally to an orthopaedic prosthesissystem, including prosthetic components and instruments for use in theperformance of an orthopaedic joint replacement procedure, and moreparticularly to orthopaedic prosthetic components and surgicalinstruments for use in the performance of a knee replacement procedure.

BACKGROUND

Joint arthroplasty is a well-known surgical procedure by which adiseased and/or damaged natural joint is replaced by a prosthetic joint.For example, in a total knee arthroplasty surgical procedure, apatient's natural knee joint is partially or totally replaced by aprosthetic knee joint or knee prosthesis. A typical knee prosthesisincludes a tibial tray, a femoral component, and a polymer insert orbearing positioned between the tibial tray and the femoral component.The tibial tray generally includes a plate having a stem extendingdistally therefrom, and the femoral component generally includes a pairof spaced apart condylar elements, which include surfaces thatarticulate with corresponding surfaces of the polymer bearing. The stemof the tibial tray is configured to be implanted in asurgically-prepared medullary canal of the patient's tibia, and thefemoral component is configured to be coupled to a surgically-prepareddistal end of a patient's femur.

From time-to-time, a revision knee surgery may need to be performed on apatient. In such a revision knee surgery, the previously-implanted kneeprosthesis, sometimes referred to a “primary knee prosthesis,” issurgically removed and a replacement or revision knee prosthesis isimplanted. In some revision knee surgeries, all of the components of theprimary knee prosthesis, including, for example, the tibial tray, thefemoral component, and the polymer bearing, may be surgically removedand replaced with revision prosthetic components. In other revision kneesurgeries, only part of the previously-implanted knee prosthesis may beremoved and replaced.

During a revision knee surgery, the orthopaedic surgeon typically uses avariety of different orthopaedic surgical instruments such as, forexample, cutting blocks, surgical reamers, drill guides, prosthetictrials, and other surgical instruments to prepare the patient's bones toreceive the knee prosthesis. Other orthopaedic surgical instruments suchas trial components may be used to size and select the components of theknee prosthesis that will replace the patient's natural joint. Trialcomponents may include a femoral trial that may be used to size andselect a prosthetic femoral component, a tibial tray trial that may beused to size and select a prosthetic tibial tray, and a stem trial thatmay be used to size and select a prosthetic stem component.

SUMMARY

An orthopaedic joint replacement system is shown and described. Thesystem includes a number of prosthetic components configured to beimplanted into a patient's knee. The system also includes a number ofsurgical instruments configured for use in preparing the bones of thepatient's knee to receive the implants. A method or technique for usingthe surgical instruments to prepare the bones is also disclosed.

According to one aspect of the disclosure, an orthopaedic surgicalinstrument system includes a surgical reamer including an elongatedshaft and a plurality of cutting flutes defined at a distal end of theelongated shaft. An attachment base includes a housing including a mainbody, an elongated bore that is sized to receive the elongated shaft ofthe reamer and extends along a longitudinal axis of the main body, and arail extending from the main body orthogonal to the longitudinal axis. Alocking knob is secured to the housing and has a longitudinal borealigned with the elongated bore of the housing that is sized to receivethe elongated shaft of the reamer. The locking knob is rotatable betweena first position in which the attachment base is permitted to slidealong the elongated shaft of the surgical reamer and a second positionin which the attachment base is locked into position on the elongatedshaft of the surgical reamer. A mounting frame is positioned on therail. The mounting frame is configured to slide relative to the housingalong the rail. A cutting block is removably coupled to the mountingframe. The locking knob is operable to advance a section of the housinginto engagement with the reamer when rotated to the second position.

In some embodiments, the housing of the attachment base may have aretaining flange configured to engage an inner rib of the locking knobto secure the locking knob to the housing. In some embodiments, thehousing of the attachment base may have an upper shaft extendingoutwardly from the main body along the longitudinal axis. The uppershaft may have a plurality of outer threads and the retaining flange.The locking knob may have a plurality of inner threads configured toengage the plurality of outer threads of the upper shaft. In someembodiments, the locking knob may be moveable along the longitudinalaxis between an engaged position in which the plurality of inner threadsare engaged with the plurality of outer threads of the upper shaft and adisengaged position in which the plurality of inner threads are spacedapart from the plurality of outer threads of the upper shaft. In someembodiments, the upper shaft may have a plurality of beams that extendalong the longitudinal axis. Each beam may be spaced apart from anadjacent beam by an elongated slot. The retaining flange may have aplurality of retaining flanges. Each retaining flange may extend from atip of each beam. In some embodiments, each beam may have a ramped uppersurface. The locking knob may have an annular rib having a conical lowersurface that may be configured to engage the ramped upper surface ofeach beam to advance the beams into engagement with the elongated shaftof the surgical reamer.

In some embodiments, the mounting frame may have a locking mechanismthat may be operable to selectively secure the mounting frame in aposition along the rail. In some embodiments, the mounting frame mayhave a second locking mechanism that may be operable to removeablycouple the cutting block to the mounting frame.

In some embodiments, the rail may have a planar outer surface. Themounting frame may have a planar inner surface that corresponds to andengages the planar outer surface of the rail to prevent the mountingframe from rotating about the rail. In some embodiments, the cuttingblock may have a plurality of cutting guides sized for insertion of acutting tool during resection of the patient's tibia. In someembodiments, an alignment guide plate may be sized to be received in oneof a plurality of cutting guides of the cutting block to assess aresection of the patient's tibia.

According to another aspect of the disclosure, an orthopaedic surgicalinstrument system includes a housing including a main body, an elongatedbore that is sized to receive an elongated shaft of a surgical reamerand that extends along a longitudinal axis of the main body, and a railextending from the main body orthogonal to the longitudinal axis. Alocking knob is secured to the housing and has a bore aligned with theelongated bore of the housing that is sized to receive the elongatedshaft of the reamer. The locking knob is rotatable between a firstposition in which the elongated bore of the housing includes an openinghaving a first diameter and a second position in which the opening ofthe elongated bore has a second diameter that is less than the firstdiameter to lock the housing into position on the elongated shaft of thesurgical reamer.

In some embodiments, the housing may have an upper shaft extendingoutwardly from the main body along the longitudinal axis. The uppershaft may have a plurality of outer threads and define the opening. Thelocking knob may have a plurality of inner threads configured to engagethe plurality of outer threads of the upper shaft. In some embodiments,the locking knob may be moveable along the longitudinal axis between anengaged position in which the plurality of inner threads are engagedwith the plurality of outer threads of the upper shaft and a disengagedposition in which the plurality of inner threads are spaced apart fromthe plurality of outer threads of the upper shaft. In some embodiments,the upper shaft may have a plurality of beams that extend along thelongitudinal axis. Each beam may be spaced apart from an adjacent beamby an elongated slot and may have a ramped upper surface. The lockingknob may have an annular rib having a conical lower surface that may beconfigured to engage the ramped upper surface to cause the beams todecrease the opening from the first diameter to the second diameter.

In some embodiments, a mounting frame may be positioned on the rail. Themounting frame may be configured to slide relative to the housing alongthe rail and may have a bracket sized to receive a cutting block. Insome embodiments, the mounting frame may have a locking mechanism thatmay be operable to selectively secure the mounting frame in a positionalong the rail. In some embodiments, a cutting block may be removablycoupled to the mounting frame.

In some embodiments, the rail may have a planar outer surface. Themounting frame may have a planar inner surface that corresponds to andengages the planar outer surface of the rail to prevent the mountingframe from rotating about the rail.

According to yet another aspect of the disclosure, an orthopaedicsurgical instrument system includes a first surgical reamer including anelongated shaft and a plurality of cutting flutes defined at a distalend of the elongated shaft. A tibial base plate includes a centralopening extending along a first longitudinal axis and a pair of fixationbores. An offset guide includes an upper drum, a lower plate sized to bepositioned in the central opening of the tibial base plate, and a boreextending through the offset guide along a second longitudinal axis thatis offset from the first longitudinal axis of the tibial base plate whenthe offset guide is positioned on the tibial base plate. The bore issized to receive the elongated shaft of the surgical reamer. A reamerguide body has a passageway defined therein that is configured to besubstantially aligned with the central opening of the tibial base platewhen the reamer guide body is positioned on the tibial base plate. Thereamer guide body also includes a pair of fixation pins. Each of thefixation pins extends downwardly from the bottom surface of the guidebody and is sized to be received in and extend outwardly from each ofthe fixation bores of the tibial base plate when the guide body ispositioned on the tibial base plate. The offset guide is operable torotate such that the lower plate of the offset guide engages the tibialbase plate to rotate the tibial base plate about the second longitudinalaxis.

In some embodiments, the offset guide may have a conical inner surfacethat defines the bore. The conical inner surface may extend from anupper opening to a lower opening smaller than the upper opening. In someembodiments, the offset guide may have a plurality of offset guides.Each offset guide may have a second longitudinal axis offset from thefirst longitudinal axis of the tibial base plate by a distance differentfrom the offsets of the other offset guides. In some embodiments, thedistance of one offset guide may be equal to zero millimeters.

In some embodiments, a second surgical reamer may be sized to extendthrough the passageway of the reamer guide body. The second surgicalreamer may have an elongated shaft and a plurality of cutting flutesdefined at a distal end. The plurality of cutting flutes may define adistal frustoconical cutting section, a proximal cutting section havinga first diameter, and a cylindrical middle cutting section having asecond diameter smaller than the first diameter.

In some embodiments, a second tibial base plate may have a centralopening and a pair of slots extending outwardly from the centralopening. A punch instrument may have a pair of arms sized to bepositioned in the pair of slots of the second tibial base plate. Eacharm may have a plurality of cutting teeth. In some embodiments, animpaction handle may have a locking flange configured to pivot between alocked position and an unlocked position. The punch instrument may havea plate configured to engage the locking flange when the locking flangeis in the locked position. In some embodiments, the impaction handle mayhave a proximal post extending along a longitudinal axis. The impactionhandle may have a bracket coupled to the proximal post and operable tomove along the longitudinal axis relative to the post. The bracket mayhave an elongated slot defined therein. The impaction handle may have alever arm that may be pivotally coupled to the proximal post. The leverarm may have the locking flange and a tab positioned in the elongatedslot defined in the bracket. When the bracket is moved in a distaldirection along the longitudinal axis, the tab may be advanced along theelongated slot and the lever arm may be pivoted from the locked positionto the unlocked position. In some embodiments, a biasing element may beoperable to bias the lever arm in the locked position.

In some embodiments, an attachment device may be configured to besecured to the elongated shaft of the first surgical reamer. A tibialcutting block may be configured to be coupled to the attachment device.

According to an aspect of the disclosure, an orthopaedic surgicalinstrument system includes a first surgical reamer including anelongated shaft and a plurality of cutting flutes defined at a distalend of the elongated shaft. A tibial base plate includes a centralopening extending along a first longitudinal axis and a pair of fixationbores. An offset guide includes an upper drum, a lower plate sized to bepositioned in the central opening of the tibial base plate, and a boreextending through the offset guide along a second longitudinal axis thatis offset from the first longitudinal axis of the tibial base plate whenthe offset guide is positioned on the tibial base plate. The bore issized to receive the elongated shaft of the surgical reamer. Anattachment device is configured to be secured to the elongated shaft ofthe first surgical reamer. The attachment device includes a locking knobsized receive the elongated shaft of the first surgical reamer. A tibialcutting block is configured to be coupled to the attachment device. Thetibial cutting block includes a cutting slot sized to receive a cuttingtool to surgically-prepare a patient's tibia to receive the tibial baseplate. The locking knob may be operable to advance a section of theattachment device into engagement with the first surgical reamer to lockthe attachment device position on the elongated shaft of the firstsurgical reamer.

In some embodiments, a second tibial base plate may have a centralopening and a pair of slots extending outwardly from the centralopening. A punch instrument may have a pair of arms sized to bepositioned in the pair of slots of the second tibial base plate. Eacharm may have a plurality of cutting teeth.

In some embodiments, an impaction handle may have a locking flangeconfigured to pivot between a locked position and an unlocked position.The punch instrument may have a plate configured to engage the lockingflange when the locking flange is in the locked position. In someembodiments, the impaction handle may have a proximal post extendingalong a longitudinal axis. The impaction handle may have a bracketcoupled to the proximal post and operable to move along the longitudinalaxis relative to the post. The bracket may have an elongated slotdefined therein. The impaction handle may have a lever arm that may bepivotally coupled to the proximal post. The lever arm may have thelocking flange and a tab positioned in the elongated slot defined in thebracket. When the bracket is moved in a distal direction along thelongitudinal axis, the tab may be advanced along the elongated slot andthe lever arm may be pivoted from the locked position to the unlockedposition. In some embodiments, a biasing element may be operable to biasthe lever arm in the locked position.

In some embodiments, a reamer guide body may have a passageway definedtherein that may be configured to be substantially aligned with thecentral opening of the tibial base plate when the reamer guide body ispositioned on the tibial base plate. In some embodiments, a secondsurgical reamer may be sized to extend through the passageway of thereamer guide body. The second surgical reamer may have an elongatedshaft and a plurality of cutting flutes defined at a distal end. Theplurality of cutting flutes may define a distal frustoconical cuttingsection, a proximal cutting section having a first diameter, and acylindrical middle cutting section having a second diameter smaller thanthe first diameter.

According to another aspect of the disclosure, a method of preparing apatient's tibia for a tibial prosthetic component includes inserting asurgical reamer into a cavity formed in a proximal end of a patient'stibia. The method also includes coupling an attachment device to anelongated shaft of the reamer such that the elongated shaft extendsthrough a bore of a locking knob and a bore of a housing of theattachment device. The method also includes rotating the locking knobabout the elongated shaft such that to compress a section of the housingengages the elongated shaft of the reamer. The method also includescoupling a mounting frame to a rail extending from the housing at anorthogonal angle with respect to the longitudinal axis. The method alsoincludes coupling a cutting block to the mounting frame. The method alsoincludes advancing a saw blade through a cutting guide formed in thecutting block to cut the proximal end of the patient's tibia.

In some embodiments, rotating the locking knob may require advancing abottom surface of the locking knob toward a shoulder surface of thehousing. In some embodiments, rotating the locking knob may requireadvancing a plurality of beams of the housing into engagement with theelongated shaft of the surgical reamer. In some embodiments, rotatingthe locking knob may require advancing an annular rib of the lockingknob into engagement with a ramped upper surface of each of theplurality of beams to advance the plurality of beams of the housing intoengagement with the elongated shaft of the surgical reamer. In someembodiments, rotating the locking knob may require engaging a threadedinner surface of the locking knob with a threaded outer surface of eachof the plurality of beams.

In some embodiments, rotating the locking knob may require gripping anangled outer surface of the locking knob. In some embodiments, themethod may require operating a locking mechanism to selectively securethe mounting frame to the rail. In some embodiments, the method mayrequire inserting the rail into a bore extending through the mountingframe such that the mounting frame moves longitudinally on the mountingpost to position the cutting block relative the patient's tibia. In someembodiments, the method may require engaging a planar outer surface ofthe mounting post with a planar inner surface of the bore of themounting frame to prevent the mounting frame from rotating about themounting post.

In some embodiments, the method may require removing the attachmentdevice, the mounting frame, and the cutting block from the patient'stibia. The method may require positioning a tibial base plate on theproximal end of the patient's tibia such that the elongated shaft of thesurgical reamer extends through a central opening of the tibial baseplate. The method may require advancing an end of the elongated shaftinto a bore defined in an offset guide, wherein the bore extends along alongitudinal axis that may be spaced apart from a longitudinal axis ofthe central opening. The method may require positioning the offset guidewithin the central opening of the tibial plate. The method may requirerotating the offset guide to rotate the tibial plate relative a proximalend of the patient's tibia. The method may require determining an offsetorientation of a tibial prosthetic component based on the orientation ofthe tibial plate relative to the proximal end of the patient's tibia.

In some embodiments, the method may require removing the offset guideand the surgical reamer from the patient's tibia. The method may requirepositioning a reamer guide body on the tibial base plate. The method mayrequire inserting a second surgical reamer into the reamer guide body.The second surgical reamer may have a plurality of cutting flutes thatdefine (i) a distal frustoconical cutting section, (ii) a proximalcutting section having a first diameter, and (iii) a cylindrical middlecutting section having a second diameter smaller than the firstdiameter.

In some embodiments, the method may require advancing a drill stop alongan elongated shaft of the second surgical reamer. In some embodiments,inserting the second surgical reamer into the reamer guide body mayrequire advancing the second surgical reamer into the patient's tibiaand using the drill stop to determine a maximum reaming depth.

In some embodiments, the method may require removing the offset guidefrom the surgical reamer, wherein the offset guide may be a first offsetguide of a plurality of offset guides. The method may require selectinga second offset guide of the plurality of offset, wherein the secondoffset guide has a second bore. The method may require advancing an endof the elongated shaft into the second bore of the second offset guide,wherein the second bore extends along a second longitudinal axis thatmay be spaced apart from the longitudinal axis of the central opening byan amount different from longitudinal axis of the first offset guide.The method may require rotating the second offset guide to rotate thetibial plate relative a proximal end of the patient's tibia to determinethe offset orientation.

According to yet another aspect of the disclosure, a method of preparinga patient's tibia for a tibial prosthetic component includes inserting afirst surgical reamer into a cavity formed in a proximal end of apatient's tibia. The method also includes positioning a tibial baseplate on the proximal end of the patient's tibia such that the elongatedshaft of the first surgical reamer extends through a central opening ofthe tibial base plate. The method also includes advancing an end of theelongated shaft into a bore defined in an offset guide, wherein the boreextends along a longitudinal axis that may be spaced apart from alongitudinal axis of the central opening. The method also includespositioning the offset guide within the central opening of the tibialplate. The method also includes rotating the offset guide to rotate thetibial base plate relative a proximal end of the patient's tibia. Themethod also includes determining an offset orientation of a tibialprosthetic component based on the orientation of the tibial platerelative to the proximal end of the patient's tibia. The method alsoincludes removing the offset guide and the first surgical reamer fromthe patient's tibia. The method also includes positioning a reamer guidebody on the tibial base plate. The method also includes inserting asecond surgical reamer into the reamer guide body, wherein the secondsurgical reamer includes a plurality of cutting flutes that define (i) adistal frustoconical cutting section, (ii) a proximal cutting sectionhaving a first diameter, and (iii) a cylindrical middle cutting sectionhaving a second diameter smaller than the first diameter.

In some embodiments, the method may require positioning a depth stop onthe elongated shaft of the second surgical reamer. The depth stop mayhave a moveable flange sized to be separately received in an aperturedefined in the elongated shaft of the second surgical reamer. The methodmay require actuating a user-operated button of the depth stop to engagethe flange with the annular slot.

In some embodiments, the method may require removing the offset guidefrom the surgical reamer, wherein the offset guide may be a first offsetguide of a plurality of offset guides. The method may require selectinga second offset guide of the plurality of offset, wherein the secondoffset guide has a second bore. The method may require advancing an endof the elongated shaft into the second bore of the second offset guide,wherein the second bore extends along a second longitudinal axis thatmay be spaced apart from the longitudinal axis of the central opening byan amount different from longitudinal axis of the first offset guide.The method may require rotating the second offset guide to rotate thetibial plate relative a proximal end of the patient's tibia to determinethe offset orientation.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the following figures,in which:

FIG. 1 is an exploded perspective view of prosthetic components of anorthopaedic joint replacement system;

FIG. 2 is a perspective view of a tibial cutting guide assembly of theorthopaedic joint replacement system;

FIG. 3 is a cross-sectional side elevation view of a portion of thecutting guide assembly of FIG. 2 taken along line 3-3 in FIG. 2;

FIG. 4 is a side elevation view of a surgical reamer of the orthopaedicjoint replacement system;

FIG. 5 is an exploded perspective view of a number of surgicalinstruments of the orthopaedic joint replacement system for use indetermining an amount of tibial offset;

FIG. 5A is a cross-sectional elevation view of an offset guide of thesurgical instruments of FIG. 5;

FIG. 6 is a perspective view of an impaction handle of the orthopaedicjoint replacement system;

FIG. 6A is a bottom perspective view of the impaction handle of FIG. 6;

FIGS. 7-21 illustrate a number of steps of a surgical procedureutilizing the orthopaedic joint replacement system;

FIG. 22 is a perspective view of another surgical reamer; and

FIGS. 22A-24 illustrate a number of steps of a surgical procedureutilizing the orthopaedic joint replacement system.

DETAILED DESCRIPTION OF THE DRAWINGS

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific exemplary embodimentsthereof have been shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the concepts of the present disclosure tothe particular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

Terms representing anatomical references, such as anterior, posterior,medial, lateral, superior, inferior, etcetera, may be used throughoutthe specification in reference to the orthopaedic implants andorthopaedic surgical instruments described herein as well as inreference to the patient's natural anatomy. Such terms havewell-understood meanings in both the study of anatomy and the field oforthopaedics. Use of such anatomical reference terms in the writtendescription and claims is intended to be consistent with theirwell-understood meanings unless noted otherwise.

The exemplary embodiments of the present disclosure are described andillustrated below to encompass prosthetic knee joints and knee jointcomponents, as well as methods of implanting and reconstructing kneejoints. It will also be apparent to those of ordinary skill in the artthat the preferred embodiments discussed below are exemplary in natureand may be reconfigured without departing from the scope and spirit ofthe present invention. However, for clarity and precision, the exemplaryembodiments as discussed below may include optional steps, methods, andfeatures that one of ordinary skill should recognize as not being arequisite to fall within the scope of the present invention.

Referring now to FIG. 1, the orthopaedic joint replacement system 10includes a number of orthopaedic prosthetic components 12 and a numberof orthopaedic surgical instruments 14 (see, for example, FIG. 2) foruse in preparing the bone to receive one or more of the prostheticcomponents 12. What is meant herein by the term “orthopaedic surgicalinstrument” or “orthopaedic surgical instrument system” is a surgicaltool for use by a surgeon in performing an orthopaedic surgicalprocedure. As such, it should be appreciated that, as used herein, theterms “orthopaedic surgical instrument” and “orthopaedic surgicalinstruments” are distinct from orthopaedic prosthetic components orimplants, such as those shown in FIG. 1.

The prosthetic components 12 of the system 10 include a prostheticfemoral component 20 configured to be secured to a surgically-prepareddistal end of a patient's femur and a prosthetic tibial component 22configured to be secured to a surgically-prepared proximal end of thepatient's tibia. In the illustrative embodiment, the tibial component 22includes a tibial tray 24 and a prosthetic insert 26 configured toengage the femoral component 20 after implantation into a patient'sknee. It should be appreciated that the system 10 may include a numberof components 12 corresponding to patients having bones of varyingsizes. In that way, a surgeon will be able to select the components andother instruments that most-closely match the patient's bony anatomy.

As shown in FIG. 1, the femoral component 20 includes an anterior flange30 and a pair of condyles 32 extending away from the flange 30. A notch34, commonly called an intra-condylar notch, is defined between thecondyles 32. The condyles 32 define articulation surfaces 36 configuredto engage corresponding articulation surfaces 70 of the insert 26. Thefemoral component 20 also includes an elongated stem post 40, whichextends superiorly away from its backside surface 42. As described ingreater detail below, the femoral stem post 40 is configured to receiveone of a number of different stem components 44. In the illustrativeembodiment, a threaded bore 48, which is sized to receive acorresponding threaded shaft 50 of a stem component 44, is defined inthe stem post 40.

The tibial tray 24 is configured to be implanted into asurgically-prepared end of a patient's proximal tibia (not shown). Thetibial tray 24 includes a platform 58 having an elongated stem post 60extending inferiorly away from its inferior surface 62. The elongatedtibial stem post 60 is configured to receive one of a number ofdifferent stem components 44. Specifically, as can be seen in FIG. 1, athreaded bore 48, which is sized to receive a corresponding threadedshaft 50 of a stem component 44, is defined in the stem post 60.

The insert 26 is securable to the tibial tray 24. In particular, theinsert 26 may be snap-fit to the tibial tray 24. In such a way, theinsert 26 is fixed relative to the tibial tray 24 (i.e., it is notrotatable or moveable in the anterior/posterior or medial/lateraldirections). Although, in other embodiments, the tibial tray may besecured in a manner that allows it to rotate relative to the tibial tray24.

The insert 26 includes lateral and medial articulation surfaces 70. Thesurfaces 70 are configured to articulate with the correspondingarticulation surfaces 36 of the femoral component 20. Specifically, thefemoral component 20 is configured to be implanted into asurgically-prepared distal end of the patient's femur (not shown), andis configured to emulate the configuration of the patient's naturalfemoral condyles. As such, the articulation surfaces 36 of the femoralcomponent 20 are configured (e.g., curved) in a manner which mimics thecondyles of the natural femur.

As shown in FIG. 1, the stem components 44 of the system 10 includeelongated stems 80, which are configured to be attached to either of thecomponents 20, 22. Each elongated stem 80 extends from the threadedshaft 50 at one end to a pointed tip 82 at the opposite end. Each stemalso includes a ribbed outer surface 84 extending from the pointed tip82 toward the threaded shaft 50. A plurality of substantially planarsurfaces 86 are positioned around the outer circumference of the stem 80adjacent to the shaft 50. The surfaces 86 are sized and positioned toreceive the end of a wrench or other installation tool so that the stem80 may be rotated into tight engagement with one of the threaded bores48.

In the illustrative embodiment, the prosthetic components 12 alsoinclude a plurality of offset adapters 90, 92 configured to be attachedto the components 20, 22. As shown in FIG. 1, the adapter 90 isconfigured to offset the longitudinal axis of the elongated stem 80 fromthe longitudinal axis of the stem post 60 of the tibial tray 24 by apredetermined amount. Similarly, the adapter 92 is configured offset thelongitudinal axis of the elongated stem 80 from the longitudinal axis ofthe stem post 40 of the femoral component 20. Each of the adapters 90,92 includes a threaded shaft 50 configured to be received in thethreaded bore 48 of either of the components 20, 22. Each of theadapters 90, 92 also includes a threaded bore 48 at its opposite end,which is sized to receive a threaded shaft 50 of one of the elongatedstems 80. In the illustrative embodiment, a locking nut 100 ispositioned on the threaded shaft 50 of each of the adapters 90, 92. Thelocking nut 100 may be typed against the surface of the stem post ofeach component to secure the adapter thereto.

The components of the knee prosthesis 10 that engage the natural bone,such as the femoral component 20, the tibial tray 24, and the stemcomponents 44, may be constructed with an implant-grade biocompatiblemetal, although other materials may also be used. Examples of suchmetals include cobalt, including cobalt alloys such as a cobalt chromealloy, titanium, including titanium alloys such as a Ti6Al4V alloy, andstainless steel. Such a metallic components may also be coated with asurface treatment, such as hydroxyapatite, to enhance biocompatibility.Moreover, the surfaces of the metallic components that engage thenatural bone may be textured to facilitate securing the components tothe bone. Such surfaces may also be porous coated to promote boneingrowth for permanent fixation.

The insert 26 may be constructed with a material that allows for smootharticulation between the insert 26 and the femoral component 20, such asa polymeric material. One such polymeric material is polyethylene suchas ultrahigh molecular weight polyethylene (UHMWPE).

Referring now to FIG. 2, the system 10 includes an attachment device 212and a cutting block 214 configured to be secured to the attachmentdevice 212. In the illustrative embodiment, the attachment device 212 isconfigured to be selectively attached to a surgical reamer 216 (see FIG.4). As described in greater detail below, the surgeon may use theattachment device 212 and the reamer 216 to position the cutting block214 for use during the resection of the proximal end of a patient'stibia.

The attachment device 212 of the system 10 includes an attachment base230 configured to be secured to the surgical reamer 216 and a mountingframe 232 configured to be moveably coupled to the base 230. Themounting frame 232 is also configured to be secured to the cutting block214, as described in greater detail below. In the illustrativeembodiment, the attachment base 230 and the mounting frame 232 areformed from a metallic material, such as, for example, stainless steelor cobalt chromium. It should be appreciated that in other embodimentsthe attachment base 230 or the mounting frame 232 may be formed from apolymeric material.

The attachment base 230 includes a housing 234, a rail 236 that extendsoutwardly from the housing 234, and a locking knob 238 that is attachedto the upper end 242 of the housing 234. The attachment base 230 has alongitudinal axis 240 extending through a lower end 244 and the upperend 242. The rail 236 has an end 246 secured to the housing 234 andextends to a cantilevered tip (see FIG. 3). In the illustrativeembodiment, the rail 236 extends orthogonal to the longitudinal axis 240of the housing 234. As shown in FIG. 2, the rail 236 has an oblongcross-section with a substantially planar top and bottom surfaces 250,252, respectively, to permit relative rotation between the attachmentbase 230 and the mounting frame 232.

Referring now to FIG. 3, the attachment base 230 has a passageway 254that extends along the axis 240 from the lower end 244 of the housing234 through the locking knob 238. The passageway 254 is sized to receivethe surgical reamer 216 and permit the base 230 to be moved along theshaft of the reamer 216 to a desired location. The housing 234 includesa main body 256 that extends from the lower end 244 to a shouldersurface 258 positioned below the knob 238. An upper shaft 260 extendsoutwardly from the shoulder surface 258 to the upper end 242 of thehousing 234, as shown in FIG. 3.

In the illustrative embodiment, the upper shaft 260 includes a pluralityof longitudinal slots 262 that divide the shaft 260 into a number ofbeams 264. Each beam 264 includes an outer plate 266 positioned on itsouter surface. As shown in FIG. 3, each plate 266 includes an uppersurface 268 that is connected to a lower surface 270 that isexternally-threaded. When viewed in cross-section, the upper surface 268is angled or ramped relative to the lower surface 270 so that the plate266 has an outer diameter at its lower end greater than at its upperend. At the upper end 242, a retaining flange 274 extends outwardly fromeach of the beams 264.

As shown in FIG. 3, the locking knob 238 includes an upper surface 276configured to be gripped by a user and a substantially planar bottomsurface 278 configured to engage the shoulder surface 258 of the housing234. A bore 280 extends through the locking knob 238 along thelongitudinal axis 240 and defines a section of the passageway 254. Inthe illustrative embodiment, the locking knob 238 includes an annularrib 282 that extends into the bore 280 near the lower end thereof. Thelocking knob 238 includes another annular rib 284 that is spaced fromand positioned above the rib 282. The annular rib 282 isinternally-threaded and may be threaded onto the lower surfaces 270 ofthe beams 264 of the base 230. As shown in FIG. 3, the annular rib 284has a conical lower surface 286 such that its inner diameter is greaterat its upper end than at its lower end. The rib 284 has an upper surface288 positioned opposite the lower surface 286. In the illustrativeembodiment, the retaining flanges 274 of the beams 264 are configured toengage the upper surface 288 to prevent the disassembly of the knob 238from the housing 234.

In use, a surgeon may position a reamer 216 in the passageway 254 of theattachment base 230. To lock the base 230 in position relative to thereamer 216, the surgeon may rotate the knob 238 clockwise about the axis240 to slide the ribs 282, 284 downward along the plates 266 of thebeams 264. The engagement between the conical lower surface 286 of therib 284 and the ramped upper surfaces 268 of the beams 264 causes thebeams 264 to bend radially inward toward the axis 240, therebycontracting the diameter of the passageway 254. In the illustrativeembodiment, when the bottom surface 278 of knob 238 is engaged with theshoulder surface 258 of the housing 234, the beams 264 are compressedagainst the reamer 216, thereby securing the attachment base 230 to thereamer 216 at a desired position. To release the attachment base 230,the surgeon may rotate the knob 238 counterclockwise and advance theknob 238 upward, thereby moving the rib 284 out of contact with theplates 266 and permitting the beams 264 bend radially outward.

Returning to FIG. 2, the system 10 also includes a mounting frame 232configured to be moveably coupled to the base 230. In the illustrativeembodiment, the mounting frame 232 includes an upper bracket 300, alower bracket 302, and a base plate 304 connecting the brackets 300,302. The upper bracket 300 includes an opening 306 sized to receive therail 236 of the attachment base 230. In the illustrative embodiment, theopening 306 is defined by a pair of substantially planar surfaces thatmatch the configuration of the surfaces 250, 252 of the rail 236. Aknurled surface 308 is positioned on each side of the bracket 300 topermit a surgeon to grip the bracket 300 to advance it along the rail236.

The upper bracket 300 also includes a locking mechanism 310, which maybe operated to secure the upper bracket (and hence the mounting frame232) to the rail 236. In the illustrative embodiment, the lockingmechanism 310 includes a user-operated handle 312 and a shaft (notshown) that extends through a bore into the opening 306. When the handle312 is rotated clockwise, the shaft 314 is advanced into engagement withthe upper surface 250 of the rail 236. It should be appreciated that inother embodiments other mechanical locking devices may be used to securethe mounting frame 232 in position relative to the rail 236.

As described above, the mounting frame 232 also includes a lower bracket302. The lower bracket 302 includes a pair of grooves 320 sized toreceive a corresponding pair of tabs 322 of the cutting block 214. Inthat way, the grooves 320 provide a mounting point for the cutting block214. Similar to the upper bracket 300, the lower bracket 302 includes alocking mechanism 324, which may be operated to secure the cutting block214 to the lower bracket 302. In the illustrative embodiment, thelocking mechanism 324 includes a user-operated handle 326 that ispositioned in a gap 328 defined between the brackets 300, 302. Thehandle 326 is attached to a shaft (not shown). When the handle 326 isrotated clockwise, the shaft may be advanced into engagement with thecutting block 214, thereby securing the block 214 to the mounting frame232. It should be appreciated that in other embodiments other mechanicallocking devices may be used to secure the mounting frame 232 to thecutting block 214.

As shown in FIG. 2 the cutting block 214 includes a posterior side wall340 that is configured to confront the anterior side of the patient'stibia, as described in greater detail below. The cutting block 214 alsoincludes an anterior side wall 342 that is positioned opposite theposterior side wall 340. An upper surface 344 connects the side walls340, 342. The upper surface 344 has a groove 346 defined between thetabs 322 described above. In the illustrative embodiment, the cuttingblock 114 is formed from a metallic material, such as, for example,stainless steel or cobalt chromium.

The cutting block 214 includes a number of cutting guides 350 that maybe used during an orthopaedic surgical procedure to resect a portion ofthe patient's bone. Each cutting guide 350 includes an elongated slotsized to receive a cutting saw blade of a surgical saw or other surgicaldevice. In the illustrative embodiment, the cutting block 214 has fourcutting guides 350 extending through the side walls 340, 342. Eachcutting guide 350 is spaced apart from the other cutting guides 350 byabout 5 millimeters and includes a planar surface 352 that defines aresection plane.

As described above, the system 10 includes a number of surgical reamersto define a passageway in the patient's tibia during the surgicalprocedure. Referring now to FIG. 4, one of the surgical reamers 216 isshown. The reamer 216 includes an elongated shaft 360 having a pluralityof cutting flutes 362 formed at a distal end 364. A tool shank 366 isformed at the opposite end and is sized to be secured to a surgicaldrill or other rotary surgical instrument. The elongated shaft 360includes a cylindrical outer surface 370 that extends from the cuttingflutes 362 to the tool shank 366. A plurality of spaced-apart annularslots 368 are defined in the outer surface 370. In the illustrativeembodiment, the position of each annular slot 368 along the outersurface 370 corresponds to a desired reaming depth of the reamer 216. Inthe illustrative embodiment, the heights of the slots 368 vary in orderto provide the surgeon with a visual indication of the different depths.

Referring now to FIG. 5, the system 10 also includes a tibial base plate400 configured to be positioned on a proximal end of a patient's tibia.It should be appreciated that the system 10 may include multiple tibialplates of different sizes generally corresponding to the variouspotential sizes of a patient's bony anatomy. The system 10 also includesa plurality of offset guides 402 configured for use with the tibial baseplate 400 and a reaming guide tower or body 404 that is also configuredfor use with the tibial plate 400. The tibial base plate 400 includes anumber of fixation pin guide holes 406, which permit the passage offixation pins 408 (see FIG. 21) to secure the tibial plate 400 to theproximal end of the patient's tibia.

The tibial base plate 400 includes a substantially planar bottom surface410 and a substantially planar top surface 412 that is positionedopposite the bottom surface 410. A curved outer side wall 414 extendsbetween the surfaces 410, 412. The tibial plate 400 also includes acentral opening 416 that extends through the surfaces 410, 412. A pairof guide bores 418 are positioned adjacent to the anterior side of thetibial plate 400. As described in greater detail below, each guide bore418 is sized to receive one of the fixation pins 420 of the reamingguide tower 404.

As shown in FIG. 5, each offset guide 402 includes an upper drum 430connected to a lower cylindrical plate 432. The cylindrical plate 432 issized to be received in the central opening 416 of the tibial plate 400.Each offset guide 402 also includes a passageway 434 that extendsthrough the drum 430 and plate 432. The amount of offset is differentfor each offset guide 402. In the illustrative embodiment, the drum 430includes a plurality of indicia 440 that cooperate with a marking 442 onthe tibial base plate 400 to provide a surgeon with an indication of theangular position of the longitudinal axis 436. When the marking 442 isaligned with one of the indicia 440, a numerical indicator correspondingto that indicia 440 may be read to determine the offset orientation.

As shown in FIG. 5A, each passageway 434 extends along a longitudinalaxis 436 that is offset from the longitudinal axis 438 of thecylindrical plate 432. In the illustrative embodiment, the elongatedshaft 360 of the reamer extends longitudinal axis 438 when the tibialbase plate 400 is positioned over the reamer. The passageway 434 isillustratively defined by a tapered inner wall 444 that extends from anupper or proximal opening 446 that is larger than the lower or distalopening 448. In other embodiments, the passageway may be cylindrical.

As described above, the system 10 also includes a reaming guide tower404. The tower 404 includes a main body 450 that extends from asubstantially planar bottom surface 452 to an upper surface 454. A guidepassageway 456 extends through the surfaces 452, 454. When the tower 404is attached to the tibial plate 400, the passageway 456 is aligned withthe central opening 416. As described above, the tower 404 includes apair of anterior fixation pins 420, which are received in the anteriorbores 418 of the tibial plate 400 when the tower is attached thereto.

Referring now to FIG. 6, an impaction handle 470 of the system 10 isshown. In the illustrative embodiment, the impaction handle is formed asan assembly from separate components made from metallic materials suchas, for example stainless steel. The impaction handle 470 includes astrike plate 472 attached to the distal end of an elongated body 474.The elongated body 474 is sized and shaped to be gripped by a surgeonduring use. The body 474 extends from the strike plate 472 to an end476. The impaction handle 470 also includes a proximal post 478 thatextends from the end 476 of the elongated body 474. The proximal post478 includes a cylindrical body section 480 that is connected to the end476, an intermediate cylindrical body section 482 extending from thebody section 480, and a proximal tip 484 extending from the section 482.The proximal tip 484 includes a substantially planar anterior surface486 that is connected to a curved posterior surface 488.

The impaction handle 470 includes an attachment mechanism 500 configuredto selectively secure other surgical instruments to the impaction handle470 during the surgical procedure. In the illustrative embodiment theattachment mechanism 500 includes a lever arm 502, which is coupled tothe post 478 and is configured to pivot relative to the proximal post478. The lever arm 502 includes a locking flange 504 that extends towardthe planar anterior surface 486 of the proximal tip 484. When the leverarm 502 is pivoted in the direction indicated by arrow 506, the lockingflange 504 is advanced away from the proximal tip 484. The lever arm 502also includes a tab 508 that extends in the direction opposite thelocking flange 504.

The attachment mechanism 500 includes a bracket 510 that is configuredto slide relative to the post 478 and the elongated body 474. Thebracket 510 is illustratively L-shaped and includes a flange 512 thatextends away from the proximal post 478. The flange 512 is connected toa slide plate 514 that extends along the body section 480. As shown inFIG. 6, the slide plate 514 has an oblong slot 516 defined therein, andthe tab 508 is positioned in the slot 516.

The bracket 510 includes a pair of tabs 522 that are received in a pairof longitudinal slots 524 defined in the cylindrical body section 480 ofthe post 478. As shown in FIG. 6A, the bracket 510 also includes a plate526 that is received in a channel 528 extending through the post 478. Abiasing element such as, for example, a spring 530 is positioned betweenthe plate 526 and the post 478 to bias the bracket 510 (and hence thelever arm 502) in the position shown in FIG. 6.

To advance the lever arm 502 in the direction indicated by arrow 506, auser may press on the flange 512 to overcome the bias exerted by thespring 530 and cause the bracket 510 to advance distally toward thestrike plate 472. As the bracket 510 advances distally, the flange 512is advanced into a channel 520 defined in the end 476 of the elongatedbody 474. Additionally, the proximal edge 522 of the slide plate 514 isadvanced into engagement with the tab 508, thereby causing the lever arm502 to pivot about its axis 532 (see FIG. 6A) and moving the lockingflange 504 away from the proximal tip 484. When the user releases theflange 512, the spring 530 urges the slide plate 514 toward the proximalend, thereby releasing the lever arm 502 to pivot toward the lockingflange 504.

The instruments 14 described may be used to surgically prepare apatient's femur to receive a prosthetic tibial component 22, one of thestem components 44, and an offset adaptor 90. In the illustrativeembodiment, the instruments 14 may be used in a revision procedure inwhich a primary implant has been removed from a proximal end of thepatient's tibia. As shown in FIG. 7, the proximal end 600 of a patient'stibia 602 in a revision procedure includes a proximal surface 604 thathas been previously-shaped to receive the primary implant. During arevision procedure, the surface 604 is resected to prepare the proximalend 600 to receive the prosthetic tibial component 22. FIGS. 7-23illustrate a number of exemplary steps of a procedure forsurgically-preparing the proximal end 600 during a revision procedure.It should be appreciated that any surgical procedure may includeadditional or fewer steps depending on the state of the patient's bonyanatomy and the preferences of the surgeon.

Referring now to FIG. 7, the surgeon may select one of the reamers 216for insertion into the intramedullary canal 608 of the patient's tibia602. The choice of reamer may depend on the size and shape of thepatient's tibia 602. As shown in FIG. 7, the surgeon may advance theselected reamer 216 into the canal 608 to straight ream the canal to apredetermined depth corresponding to one of the annular slots 368.

The surgeon may leave the reamer 216 in place at the predetermined depthwhile assembling the attachment device 212. As described above, thesurgeon may attach the cutting block 214 to the mounting frame 232 andsecuring the instruments together by operating the handle 326. Thesurgeon may slide the mounting frame 232 along the rail 236 of theattachment base 230 and lock the frame 232 in position relative to thebase 230 by operating the other handle 312. As shown in FIG. 8, thesurgeon may place the assembled attachment device 212 on the elongatedshaft 360 of the reamer 216. To do so, the surgeon may align thepassageway 254 of the attachment device 212 with the shank 366 of thereamer 216 and then advance the attachment device 212 over the shank 366and down the elongated shaft 360 toward the tibia 602.

As shown in FIGS. 9-10, a surgeon may utilize a number of differentgauges 620, 622 to determine where to place the cutting block 214relative to the bone 602. Each of the gauges 620, 622 has a probe tip624 configured to engage the proximal surface 604 when the cutting block214 is properly positioned relative to the tibia 602. In theillustrative embodiment, each gauge is selectively attached to thecutting block 214 via a mounting flange 626 sized to be positioned inthe cutting guides 350 of the block 214. The gauge 622 is alsoadjustable such that the probe tip 624 may be set at different heightsrelative to its mounting flange 626 (and hence the cutting block 214).The surgeon may slide the attachment device 212 and cutting block 214along the reamer 216 in the directions indicated by arrows 630 in FIGS.9-10 until the cutting block 214 is properly positioned to guide theresection of the proximal surface 604.

The surgeon may then lock the attachment device 212 at the desiredposition by operating the control knob 238. When the knob 238 is rotatedclockwise, the ribs 282, 284 of the knob 238 cause the diameter of thepassageway 254 to contract, as described above. In the illustrativeembodiment, when the bottom surface 278 of knob 238 is engaged with theshoulder surface 258 of the housing 234, the attachment base 230 engagesthe reamer 216, thereby locking the cutting block 214 in positionrelative to the bone. The surgeon may also selectively operate thehandle 312 to free the mounting frame 232 (and hence the cutting block214) for movement along the rail 236. In that way, the surgeon may alsoadjust the position of the cutting block 214 relative to the anteriorface of the tibia 602.

As shown in FIG. 11, the surgeon may utilize a number of fixation pins420 to secure the cutting block 214 to the tibia 602. The surgeon maythen detach the cutting block 214 from the attachment device 212 byoperating both handles 312, 326 to release the mounting frame 232 fromthe cutting block 214 and the attachment base 230. After sliding themounting frame 232 off the rail 236, the surgeon may release theattachment base 230 from the reamer 216 by operating the control knob238.

Referring now to FIG. 12, the surgeon may also remove the reamer 216from the canal 608 before resecting the tibia 602. To perform theresection, the surgeon may advance a surgical saw 640 through one of thecutting guide slots 350 into contact with the patient's bone. Thesurgeon may then use the saw 640 to remove material from the end 600 ofthe patient's tibia 602 and create a new surgically-prepared proximalsurface shaped to receive a prosthetic tibial component 22.

Referring now to FIGS. 13-14, surgeon may utilize the reamer 216 and thetibial plate 400 to determine whether an offset adaptor 90 should beincluded in the tibial prosthetic assembly. To do so, surgeon may insertthe reamer 216 into the intramedullary canal 608, as shown in FIG. 13.The surgeon may position the tibial plate 400 on the proximal end 600 ofthe patient's tibia 602. As shown in FIG. 14, the center of the opening416 of the tibial plate 400 is offset from the longitudinal axis of thereamer 216, indicating the need to use an offset adapter 90 in thetibial prosthetic assembly.

As shown in FIG. 15, the surgeon may select an offset guide 402 andadvance along the reamer 216 into contact with the tibial plate 400positioned on the patient's tibia 602. With the offset guide 402 seatedon the tibial plate 400, the surgeon may grip the contoured outersurface of the guide 402 to turn the guide 402 about the reamer 216 asindicated in FIG. 15 by arrows 650. As the guide 402 is turned, thetibial plate 400 is rotated about the proximal surface 604 of thepatient's tibia 602. That movement changes the offset orientation of theguide 402 and tibial plate 400 relative to the reamer 216. The surgeonmay continue to turn the guide 402 until the tibial plate 400 is placedin a location on the patient's tibia 602 that offers maximum coverage ofthe surgically-prepared proximal surface 604. When the base plate 400 isin the desired location on the patient's tibia 602, the surgeonidentifies the indicia 440 that is aligned with the mark 442 and readsthe numerical indicator associated with the indicia 440 to identify theselected offset orientation, as shown in FIG. 16. It should beappreciated that the surgeon may repeat this process with other offsetguides 402 having different amounts of offset until the tibial plate 400is placed in a location on the patient's tibia 602 that offers maximumcoverage of the proximal surface 604. When the tibial plate 400 ispositioned at a desired location on the patient's tibia 602, the surgeonmay utilize one or more fixation pins 408 to secure the tibial plate 400and the position, as shown in FIG. 16. The surgeon may then remove theoffset guide 402 from the tibial plate 400 and the reamer 216, as shownin FIG. 17.

Referring now to FIG. 18, the surgeon may perform another reamingoperation utilizing a larger diameter reamer 702 continue reshaping thecanal 608. As shown in FIG. 19, the surgeon may also utilize the reamingguide tower 404 with the tibial plate 400. To do so, the surgeon mayalign the fixation pins 420 of the tower 404 with the guide holes 418 ofthe tibial plate 400. The surgeon may then advance the fixation pins 420through the guide holes 418 and into the proximal end 600 of thepatient's tibia 602.

Referring now to FIGS. 20-22, the surgeon may utilize another reamer 704with the tower 404. The system 10 also includes a moveable depth stop710, which be attached to any of the reamers at an annular slot 642corresponding to a desired depth. In the illustrative embodiment, thedepth stop 710 has a central opening 712 and a plurality of alignmenttabs 714 extending inwardly into the opening 712. The central opening712 has a diameter corresponding to the largest diameter reamer in thesystem 10. Each reamer, including the reamer 704, includes a pluralityof longitudinal slots 716 corresponding in number to the number ofalignment tabs 714 of the depth stop 710. As shown in FIG. 20, thebottom surfaces of the slots 716 of each reamer are positioned and sizedto be received in an alignment opening 720 defined by the tips of thetabs 714 so that a single depth stop 710 may be used with any sizereamer.

In the illustrative embodiment, the depth stop 710 includes a movableplate 722 having a pin that may be advanced into and out of engagementwith the annular slot 642 or other aperture to secure the depth stop ata desired position.

As shown in FIG. 21, when the depth stop 710 is properly positioned atthe desired annular slot 642 of the reamer 704, the reamer 704 may beadvanced into the central cylindrical passageway of a reaming guideadaptor 724 positioned in the guide tower 404. The reamer 704 may thenbe advanced along the guide adaptor 724 and into contact with theproximal end 600 of the patient's tibia 602. The surgeon may continue toadvance the reamer 704 deeper into the patient's tibia until the depthstop 710 contacts the guide adapter 724, thereby reshaping the canal 608as desired. It should also be appreciated that in some embodiments thereamer and the depth stop 710 may be used with the guide tower alone.

Returning to FIGS. 22-22A, the reamer 704 is shown with the guide tower404. Similar to the reamer 216, the reamer 704 includes an elongatedshaft 730 having a plurality of cutting flutes 732 formed at a distalend 734. A tool shank 736 is formed at the opposite end and is sized tobe secured to a surgical drill or other rotary surgical instrument. Theelongated shaft 730 includes an outer surface 740 that extends from thecutting flutes 732 to the tool shank 736, and the plurality oflongitudinal slots 716 are defined in the outer surface 740.

As shown in FIG. 22, the plurality of cutting flutes 732 include afrustoconical distal section 750 that extends from the distal end 734.The distal section 750 is connected at an edge 752 to a cylindricalmiddle section 754 of the cutting flutes 732 (i.e., the edges of cuttingflutes 732 define a cylindrical shape). The middle section 754 has adiameter 756. The middle section 754 is connected to a proximal section758 via a tapered section 760. In the illustrative embodiment, theproximal section 758 has a diameter 762 that is greater than thediameter 756 of the middle section 754. The combination of thecylindrical middle section 754, tapered section 760, and proximalsection 758 of the cutting flutes 732 cooperate to define an opening apatient's tibia shaped to match the offset adaptor 90 of the prosthetictibial component 22, as indicated in broken line in FIG. 22A.

Referring now to FIG. 23, the surgeon may select a keel punch 660 toresize the canal 608 to receive a portion of the elongated stem post 60of the tibial tray 24. The keel punch 660 includes a pair of arms 662extending outwardly from a central body 664. Each of the arms 662includes a number of downwardly-extending cutting teeth 668 thepatient's bone to create a passageway for the elongated stem post 60.The central body 664 includes an undercut 670 sized to receive theflange 504 of the lever arm 502 of the impaction handle 470. The centralbody 664 also includes an engagement plate 672 positioned above theundercut 670, which is configured to engage the locking flange 504, asshown in FIG. 23.

To secure the keel punch 660 the impaction handle 470, a user may presson the flange 512 to cause the bracket 510 of the handle 470 to advancedistally toward the strike plate 472. As the bracket 510 advancesdistally, the flange 512 is advanced into a channel 520 defined in theend 476 of the elongated body 474. Additionally, the proximal edge 522of the slide plate 514 is advanced into engagement with the tab 508,thereby causing the lever arm 502 to pivot about its axis and moving thelocking flange 504 away from the proximal tip 484. The keel punch 660may then be advanced over the proximal tip 484 and into contact with thecylindrical body section 482, as shown in FIG. 23. The user may thenrelease the flange 512 and a biasing element 530 of the handle 470 urgesthe bracket 510 proximally, thereby moving the locking flange 504 towardthe proximal tip 484 and into engagement with the engagement plate 672to secure the keel punch 660 to the handle 470.

As shown in FIG. 24, the surgeon may remove the tibial plate 400 fromthe proximal end 600 of the patient's tibia 602 and replace it withanother tibial plate 690 including openings 692 sized to receive thearms 662 of the keel punch 660. The surgeon may then advance theimpaction handle 470 and keel punch 660 toward the tibial plate 690, asindicated by arrow 694. As the keel punch 660 passes through the tibialplate 690, the cutting teeth 668 engage the patient's bone and reshapethe canal to receive the elongated post 60 of the tibial prostheticcomponent 22.

While the foregoing exemplary embodiments have been described to have aseparable tibial tray and a tibial tray insert, it is to be understoodthat the tibial tray may include condyle receiver bearing surfaces thatobviate the need for a separate tibial tray insert.

Following from the above description and invention summaries, it shouldbe apparent to those of ordinary skill in the art that, while themethods and apparatuses herein described constitute exemplaryembodiments of the present invention, the invention contained herein isnot limited to this precise embodiment and that changes may be made tosuch embodiments without departing from the scope of the invention asdefined by the claims. Additionally, it is to be understood that theinvention is defined by the claims and it is not intended that anylimitations or elements describing the exemplary embodiments set forthherein are to be incorporated into the interpretation of any claimelement unless such limitation or element is explicitly stated.Likewise, it is to be understood that it is not necessary to meet any orall of the identified advantages or objects of the invention disclosedherein in order to fall within the scope of any claims, since theinvention is defined by the claims and since inherent and/or unforeseenadvantages of the present invention may exist even though they may nothave been explicitly discussed herein.

1. An orthopaedic surgical instrument system comprising: a first surgical reamer including an elongated shaft and a plurality of cutting flutes defined at a distal end of the elongated shaft, a tibial base plate including a central opening extending along a first longitudinal axis and a pair of fixation bores, an offset guide including an upper drum, a lower plate sized to be positioned in the central opening of the tibial base plate, and a bore extending through the offset guide along a second longitudinal axis that is offset from the first longitudinal axis of the tibial base plate when the offset guide is positioned on the tibial base plate, the bore being sized to receive the elongated shaft of the surgical reamer, and a reamer guide body having a passageway defined therein that is configured to be substantially aligned with the central opening of the tibial base plate when the reamer guide body is positioned on the tibial base plate, and a pair of fixation pins, each of the fixation pins extending downwardly from the bottom surface of the guide body and sized to be received in and extend outwardly from each of the fixation bores of the tibial base plate when the guide body is positioned on the tibial base plate, wherein the offset guide is operable to rotate such that the lower plate of the offset guide engages the tibial base plate to rotate the tibial base plate about the second longitudinal axis.
 2. The orthopaedic surgical instrument system of claim 1, wherein the offset guide includes a conical inner surface that defines the bore, the conical inner surface extending from an upper opening to a lower opening smaller than the upper opening.
 3. The orthopaedic surgical instrument system of claim 1, wherein the offset guide includes a plurality of offset guides, each offset guide having a second longitudinal axis offset from the first longitudinal axis of the tibial base plate by a distance different from the offsets of the other offset guides.
 4. The orthopaedic surgical instrument system of claim 3, wherein the distance of one offset guide is equal to zero millimeters.
 5. The orthopaedic surgical instrument system of claim 1, further comprising a second surgical reamer sized to extend through the passageway of the reamer guide body, the second surgical reamer having an elongated shaft and a plurality of cutting flutes defined at a distal end, wherein the plurality of cutting flutes define (i) a distal frustoconical cutting section, (ii) a proximal cutting section having a first diameter, and (iii) a cylindrical middle cutting section having a second diameter smaller than the first diameter.
 6. The orthopaedic surgical instrument system of claim 1, further comprising: a second tibial base plate including a central opening and a pair of slots extending outwardly from the central opening, and a punch instrument including a pair of arms sized to be positioned in the pair of slots of the second tibial base plate, each arm including a plurality of cutting teeth.
 7. The orthopaedic surgical instrument system of claim 6, further comprising an impaction handle including a locking flange configured to pivot between a locked position and an unlocked position, wherein the punch instrument includes a plate configured to engage the locking flange when the locking flange is in the locked position.
 8. The orthopaedic surgical instrument system of claim 7, wherein the impaction handle further includes: a proximal post extending along a longitudinal axis, a bracket coupled to the proximal post and operable to move along the longitudinal axis relative to the post, the bracket having an elongated slot defined therein, a lever arm that is pivotally coupled to the proximal post, the lever arm including the locking flange and a tab positioned in the elongated slot defined in the bracket, wherein when the bracket is moved in a distal direction along the longitudinal axis, the tab is advanced along the elongated slot and the lever arm is pivoted from the locked position to the unlocked position.
 9. The orthopaedic surgical instrument system of claim 8, further comprising a biasing element operable to bias the lever arm in the locked position.
 10. The orthopaedic surgical instrument system of claim 1, further comprising: an attachment device configured to be secured to the elongated shaft of the first surgical reamer, a tibial cutting block configured to be coupled to the attachment device.
 11. An orthopaedic surgical instrument system comprising: a first surgical reamer including an elongated shaft and a plurality of cutting flutes defined at a distal end of the elongated shaft, a tibial base plate including a central opening extending along a first longitudinal axis and a pair of fixation bores, an offset guide including an upper drum, a lower plate sized to be positioned in the central opening of the tibial base plate, and a bore extending through the offset guide along a second longitudinal axis that is offset from the first longitudinal axis of the tibial base plate when the offset guide is positioned on the tibial base plate, the bore being sized to receive the elongated shaft of the surgical reamer, an attachment device configured to be secured to the elongated shaft of the first surgical reamer, the attachment device including a locking knob sized receive the elongated shaft of the first surgical reamer, and a tibial cutting block configured to be coupled to the attachment device, the tibial cutting block including a cutting slot sized to receive a cutting tool to surgically-prepare a patient's tibia to receive the tibial base plate, wherein the locking knob is operable to advance a section of the attachment device into engagement with the first surgical reamer to lock the attachment device position on the elongated shaft of the first surgical reamer.
 12. The orthopaedic surgical instrument system of claim 11, further comprising: a second tibial base plate including a central opening and a pair of slots extending outwardly from the central opening, and a punch instrument including a pair of arms sized to be positioned in the pair of slots of the second tibial base plate, each arm including a plurality of cutting teeth.
 13. The orthopaedic surgical instrument system of claim 12, further comprising an impaction handle including a locking flange configured to pivot between a locked position and an unlocked position, wherein the punch instrument includes a plate configured to engage the locking flange when the locking flange is in the locked position.
 14. The orthopaedic surgical instrument system of claim 13, wherein the impaction handle further includes: a proximal post extending along a longitudinal axis, a bracket coupled to the proximal post and operable to move along the longitudinal axis relative to the post, the bracket having an elongated slot defined therein, a lever arm that is pivotally coupled to the proximal post, the lever arm including the locking flange and a tab positioned in the elongated slot defined in the bracket, wherein when the bracket is moved in a distal direction along the longitudinal axis, the tab is advanced along the elongated slot and the lever arm is pivoted from the locked position to the unlocked position.
 15. The orthopaedic surgical instrument system of claim 14, further comprising a biasing element operable to bias the lever arm in the locked position.
 16. The orthopaedic surgical instrument system of claim 11, further comprising a reamer guide body having a passageway defined therein that is configured to be substantially aligned with the central opening of the tibial base plate when the reamer guide body is positioned on the tibial base plate.
 17. The orthopaedic surgical instrument system of claim 16, further comprising a second surgical reamer sized to extend through the passageway of the reamer guide body, the second surgical reamer having an elongated shaft and a plurality of cutting flutes defined at a distal end, wherein the plurality of cutting flutes define (i) a distal frustoconical cutting section, (ii) a proximal cutting section having a first diameter, and (iii) a cylindrical middle cutting section having a second diameter smaller than the first diameter. 